Color oscillograph processing

ABSTRACT

AN IMPROVEMENT IN A PROCESS FOR DEVELOPING MULTICOLORED PHOTOGRAPHIC TRACE RECORDING MATERIAL, THE TRACE MATERIAL CONSISTING OF A LIGHT-COLORED SUPPORTING SHEET HAVING SUPERPOSED THEREON AT LEAST TWO LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYERS EACH ONE OF WHICH IS SENSITIVE TO LIGHT OF DIFFERENT WAVE LENGTHS AND EACH ONE OF WHICH CONTAINS A NON-DIFFUSING COLOR FORMER, WHICH COMPRISES PASSING THE MATERIAL, AFTER TRACE RECORDING EXPOSURE TO LIGHT OF DIFFERENT COLORS, PROGRESSIVELY AND IN SEQUENCE THROUGH AN AQUEOUS CAUSTIC ALKALI SOLUTION, AN AQUEOUS COLOR DEVELOPER SOLUTION AN AN AQUEOUS FIXER SOLUTION.

Unied States 3,556,789 COLOR OSCILLOGRAPH PROCESSING Carl E. Johnson and Dewey M. Dumers, Bi-nghamton, N.Y., assignors to GAF Corporation, New York, N.Y., a corporation of Delaware N0 Drawing. Filed Nov. 15, 1967, Ser. No. 683,148 Int. Cl. G03c 5/38, 7/16 US. C]. 96-22 2 Claims ABSTRACT OF THE DISCLOSURE An improvement in a process for developing multicolored photographic trace recording material, the trace material consisting of a light-colored supporting sheet having superposed thereon at least two light-sensitive silver halide emulsion layers each one of which is sensitive to light of different wave lengths and each one of which contains a non-diffusing color lformer, which comprises passing the material, after trace recording exposure to light of different colors, progressively and in sequence through an aqueous caustic alkali solution, an aqueous color developer solution and an aqueous fixer solution.

This invention relates to a process for developing photosensitive trace recording material and, more particularly, to the process for developing oscillograph traces having at least three colors.

Photosensitive silver halide papers adapted for trace recording are known. Such materials are both of the print-out type and the developing-out type. The printout type requires no development step and may or may not be fixed. Such materials are generally much slower, however, than the materials used in developing-out processes and have poor image permanency. The developingout type, as the name implies, requires that the exposed material be chemically developed, fixed and washed in order to provide a stable visible image. It is the latter type of trace recording material with which the present invention is concerned.

As photographic trace recording, e.g., oscillograph recording, has increased in importance, there have evolved fields of use in which a multi-colored recording is desirable. Wind tunnel and flight testing are examples of procedures where a plurality of colored traces is of considerable value. Trace separation and read-out of recorded data, of course, improves efiiciency of inspection under changing conditions of operation. Further, recording of test results which can be visually observed after a relatively brief interval of time and use of a simplified system of processing with a minimum number of solutions are desirable.

The preparation and use of developing-out material suitable for color oscillograph recording is described, for example, in our co-pending patent application Ser. No. 462,063 filed June 7, 1965, now US. Patent 3,499,758 and corresponding German Utility Patent No. 1,952,682, issued Dec. 29, 1966.

Processing was accomplished by placing exposed material in a standard automatic oscillogram processor as manufactured by Consolidated Electrodynamics Corp. and processed at a rate of about 4 feet/ minute. The processing apparatus comprised 4 tanks, through which the exposed material passed in sequence, each maintained at a temperature of about 100 F., and having the following contents:

Tank number: Contents 1 Color Developer. 2 Do. 3 Fixer. 4 Do.

Use of two developer tanks and two fixer tanks made possible extension of the processing time and the useful life of the processing solutions. The color developer and fixer contained the following ingredients in the tollowing amounts:

COLOR DEVELOPER Ingredient: Amount, grams Sodium pyrophosphate 1.0 Sodium sulfite (anhydrous) 4.0 Sodium carbonate (monohydrate) 60.0 Potassium bromide 1.0 4-N,N-di(fi-hydroxyethyl)aminoaniline 7.5 Water, sufficient to make 1 liter. pH 10.6

FIXER Ingredient: Amount, grams Sodium thiosulfate (anhydrous) 130.0 Water, sufiicient to make 1 liter.

Such processing of the paper has a number of shortcomings, such as a pH drop over the developing period, reduction in developer volume and resulting loss in development power, variation in concentration of color eveloping agent in the processed paper when dry, and finally, the necessity to store liquid replenisher.

It is an object of this invention, therefore, to provide a process for developing color oscillographic paper which will overcome the aforesaid shortcomings.

In accordance with this invention, it has been found that replacement of the developer solution in the first tank with dilute aqueous caustic alkali overcomes the deficiencies of the prior process and, at the same time, results in a final print having added clarity and better uniformity.

More specifically, it Was found that replacement of the developer solution in the first tank by a sodium hydroxide pre-bath solution eliminates the usual pH drop which otherwise occurs after a few hundred feet of film are processed, eliminates the loss of developing power resulting from reduction in developer solution level in the first tank While increasing the energy of the developer solution in the second tank, reduces the color developing agent concentration in the dry processed paper whereby processed record stability is increased, and finally makes possible replenishment of the developer solution by addition of dry developing agent to the second tank.

The improved process increases the developer solution capacity. Thus, up to 800 sq. ft. of continuous rolls of color oscillograph paper can be processed with minimum losses in speed, gradation and record stability, and the ease of developer replenishment results in a simplified continuous replenishment system.

Color photographic trace recording material suitable for processing according to this invention comprise a light colored opaque background support and at least two superposed light-sensitive silver halide emulsion layers, respectively sensitive to light of different wave length ranges, and respectively containing color formers yielding different colorations on color development. Thus, a color photographic trace recording material suitable for processing in accordance with the present invention comprises a flexible support bearing on at least one surface thereof (a) an undercoat comprising a silver chlorobromide emulsion layer of low blue sensitivity (i.e. practically veloping agent to form a magneta dye image; (b) a separating layer comprising a hardened gelatin layer (c) an outer coating comprising a silver bromoiodide emulsion layer having a high sensitivity to blue light without an optical sensitizing dye, but containing a color former capable of forming a cyan dye image upon color development; and (d) a hardened gelatin surface layer.

While the emulsions may be applied to any suitable light colored supporting sheet material, such as pigmented film or paper, it is preferable to use paper such as 4590 grams/ square meter Document paper (100% rag) without baryta coat or other surface coating, or a paper similar thereto.

The color photographic recording material is exposed to light in an oscillograph recorder, provided with suitable colored filters in front of the measurement indicator used in conjunction therewith. An entire roll of a record paper is exposed to record the information and then chemically developed. For example, a record roll of ap proximately 250-400 feet in length is entirely exposed before its removal from the recorder and its subsequent development.

The color formers employed in the emulsions are those which are well known in the photographic art. They are essentially colorless compounds fast to diffusion and capable of reacting with the oxidation products of an aromatic p-amino developing agent, particularly an N,N- disubstituted p-phenylenediamine such as N,N-diethylamino aniline, N,N-d i-(B-hydroxyethyl)-aniline and the like, to produce dyes of the azomethine, quinoneimine, indoaniline and phenazine (azine) series. Such color formers are described for instance in United States Patents 2,500,487; 2,829,975 and others. Illustrative of color formers which are usable in accordance with this invention are 1-octadecyl-2-(2'-l-hydroxynaphthyl)-benzimidazole-S-sulfonic acid as a cyan color former; 1-(4' phenoxy-3-sulphophenyl)-3-stearyl-5-pyrazole as a ma genta color former; and 2-(4'-benzoylacetaminophenyl) 1-octadecylbenzimidazole-S-sulfonic acid as a cyan color former; l-(4'-phenoxy-3"-sulphophenyl) -3-stearyl-5-pyrazole as a magenta color former; and 2-(4'-benzoylacetaminophenyl) 1-octadecylbenzimidazole-S-sulfonic acid as a yellow color former. Generally speaking the quantity of color former used per unit of silver halide is selected in such a way that sufl rcient density of the trace is achieved upon exposure and developing so as to provide proper readout. Specifically, the ratio of color former to silver halide per silver halide emulsion layer may be about millimols of color former to about 2 to grams of silver halide.

A sensitizing dye capable of sensitizing in the green region of the spectrum is employed in one emulsion layer. If desired, the blue sensitivity of the other emulsion layer can be further increased by the use of a sensitizing dye for the blue. It is preferred that these dyes should be nonmigratory in the emulsion in which they are present so that the dyes cannot wander freely from layer to layer. Examples of sensitizing dyes usable herein are the various cyanine, carbocyanine, merocyanine, styryl and related sensitizing dyes which are well known to persons skilled in the art.

The emulsions may contain the usual coating finals such as those proposed to retard or prevent fog in light-sensitive silver halide emulsions. These compounds are commonly referred to as antifoggants or stabilizers and are, in many instances, heterocyclic compounds with a plurality of nitrogen atoms or with a mercapto group in their molecule.

Certain other adjuvants normally incorporated into silver halide photographic emulsions, such as wetting agents, may also be employed.

The aqueous gelatin dispersions and gelatin silver halide emulsions employed herein are preferably treated with a hardening agent in order to reduce the tendency of the layers to soften, melt or reticulate during processing, particularly" at temperatures which are higher than 68 F. (20 C.) heretofore specified for the processing of photographic materials. Compounds which have been used for the hardening of gelatin and gelatin emulsion layers include formaldehyde, hydroxyaldehydes, glyoxal and its derivatives, triacrylformal, as well as mixtures of such aliphatic aldehydes with an aromatic hydroxy compound such as phenol, or resorcylic aldehyde. Other conventional hardeners include alum, chromalum, chromium acetate and the like.

Suitable supports for the silver halide emulsion layers processed according to this invention include the flexible supports used in the prior art for oscillographic recordings. These should be light colored and opaque. In general, a photographic grade flexible paper is selected. In this regard, 55 g./m. of Document paper rag) without a baryta coating or other surface coating is especially preferred. However, there can .be used any other flexible light colored opaque material suitable for coating with a photographic colloid silver halide emulsion.

The following example illustrates the invention and the manner of carrying it out. However, the invention should not be considered as being limited to the details thereof.

Example Galvanometor identification Filter Transmission Absorption A Yellow 580 through 700 Blue.

B Magne-nta 455 and 700 Green.

C Pale magnenta 455 and 700 Predominantly color correction. green.

D None The lamp voltage was set at 12 volts and paper travel rate was adjusted at 2.5 inches/ second.

In order to expose the recording paper, signal generators were used to apply a sine wave of 20 cycles/ second to each galvanometer and the amplitude was varied to give a trace deflection of from 1 to 4 inches.

The exposed material was then placed in a standard automatic oscillogram processor (e.g. as manufactured by Consolidated Electrodynamics Corp.) and processed at a rate of about 8 feet/ minute. In such processor apparatus 4 tanks were utilized, each being maintained at a temperature of about 100 F with the following tank arrangement as to contents:

Tank number: Contents 1 Sodium hydroxide solution. 2 Color developer. 3 Fixer.

The concentrations of the various ingredients in the above four tanks are given below.

SODIUM HYDROXIDE SOLUTION (TANK NO. 1)

Ingredient: Amount, grams Sodium pyrophosphate 6.0 Sodium hydroxide, anhydrous 95.

Water to make 6 quarts.

COLOR DEVELOPER (TANK NO. 2)

Ingredient: Amount, grams Sodium pyrophosphate 4.0 Sodium sulfite, anhydrous 16.0 Sodium hydroxide, 76% flake M 9.40 Potassium bromide 8.0 4-N,N-di(p-hydroxyethyl)aminoiline 30.0

Water to make 4 quarts.

FIXER (TANKS NOS. 3 AND 4) Ingredient: Amount, grams Sodium pyrophosphate 4.0 Sodium thiosulfate, anhydrous 520.0 Sodium sulfite, anhydrous 16.0

Water to make 4.0 quarts.

The resulting processed paper showed four distinct and separate traces, namely, cyan, magenta, deep blue and purple. The magenta trace was produced by the light from galvanometer A which was fitted with the yellow filter. The cyan trace was produced by the light from galvanometer B which was fitted with the magenta filter. The deep blue trace was produced by the light from galvanometer C which was fitted with the pale magenta colorcorrection filter and the purple trace by the light from galvanometer D, which was not fitted with a filter.

After processing 400 feet of paper, the developer in Tank No. 2 was replenished by adding 4-N,N-di(;8-hydroxyethyl)arninoaniline in an amount equal to about one half the quantity initially employed. No pH drop occurred in the solution of Tank No. 2 during the processing. Since the alkaline solution carried over from Tank No. 1 to Tank No. 2 increased the energy of the developer in the latter, the rate of development remained high despite progressive reduction in level of the developer solution. The color developing agent remaining in the paper on completion of processing was reduced by about 60% as compared with the use of two developer tanks.

The caustic alkaline pre-bath may contain as the alkaline agent sodium or potassium hydroxide in a concentration preferably ranging from 0.5 to A small amount (e.g. 540% of the quantity of caustic alkali) of a phosphate or similar reagent may be added as a water softener.

Variations which will be obvious to those skilled in the art can be made in the foregoing procedure without departing from the scope of our invention.

What is claimed is:

1. In a process for the development of multi-color photographic trace recording material having, on an opaque light-colored supporting sheet material, at least two superposed light-sensitive silver halide emulsion layers, respectively sensitive to light of different wave length ranges and respectively containing non-diffusing color formers yielding different colors with the oxidation products of aromatic para-amino color developers, the steps of which include passing said material, after trace recording exposure to light of different colors, progressively and in sequence through an aqueous color developer solution and an aqueous fixer solution, the improvement which comprises passing said material through an aqueous developer-free, caustic alkali solution prior to passing through the developer and fixer solutions.

2. A process as defined in claim 1, wherein said doveloper-free, caustic alkali solution contains from 0.5 to 10% of an alkali metal hydroxide.

References Cited UNITED STATES PATENTS 3,335,004 8/1967 Wrisley et al. 9622 WILLIAM D. MARTIN, Primary Examiner M. SOFOCLEOUS, Assistant Examiner U.S. Cl. X.R. 9655, 61 

